The Potomac River: Its Future Depends On Us

The story of the river today and its future is mixed.  It may be at a critical turning point.

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Every spring, little two- to six-inch minnows called creek chubs migrate up the Potomac River with their mouths full of gravel to build mound-shaped nests on the riverbed in hopes of attracting females who, if they choose to spawn, deposit around 25 to 30 fertilized eggs. 

Other minnows lay their eggs in the chubs’ nests too.  Hundreds of shiny, colorful minnows swirling around the nest can look like a disjointed merry-go-round. This is just one of millions of underwater dramas in the Potomac River that few people see. This is a good sign.

What people do see more readily are plastic bottles, six-pack rings, cans, Styrofoam pieces and other discarded detritus of humanity littering the river.  In Oxon Cove, an avalanche of trash — wipes, bottles, bicycles, shopping carts, syringes, fire extinguishers and more — is buried in the sediment and has become an island the size of two football fields. That’s a bad sign.

The story of the river today and its future is mixed. It may be at a critical turning point.

How Is the River Doing?

When English Captain John Smith sailed up the Potomac in 1608, he marveled at the abundance of fish “lying so thick with their heads above the water” that he caught them with a frying pan.  By 1951, it was “an open sewer,” denounced the Washington Post, and in 1965 President Lyndon B. Johnson decried the river as “a national disgrace.”  American Rivers listed it as “America’s most endangered river” in 2012.

The Potomac is clearly cleaner today, but the Potomac Conservancy’s 2020 assessment, based on 2018 and 2019 data, shows the first decline in a decade, down from a B in 2019 to a B-, but substantially improved from its 2011 D grade.  

Overall

The Potomac gurgles up near Thomas, West Virginia, at 3,140 feet above sea level and winds 383 miles past Maryland, Washington, D. C., and Virginia to the Chesapeake Bay.  On average, seven billion gallons flow daily and 486 million gallons are withdrawn for drinking water for five million of the basin’s six million people.  An ever-present backdrop for the region, in the 19th century, it was a major commercial artery serving Alexandria’s thriving port, once one of the ten busiest ports in America. Today, it is a coveted site in the city for waterfront condominiums, dining and recreation. Maryland owns most of the river.

Still Not Healthy

While wastewater treatment upgrades have improved water quality, stormwater runoff from urban and suburban development is the fastest growing pollutant and “threatens to undo decades of progress,” concludes the Conservancy.  Parking lots, roads and roofs block the land’s natural ability to absorb rainwater and whisk polluted water into streams and the river. 

The Conservancy gave the river an F for forested shoreline buffers which filter pollutants and slow down stormwater flows. “Population growth and the infrastructure to support sprawling development patterns threaten to exacerbate the problem as forests are torn down and replaced with parking lots, housing and roads,” the report maintains.  

The Potomac Riverkeeper’s tests of water samples for E. coli bacteria at 10 sites find that public health standards are met half the time.  For three sites — Oronoco Bay, National Harbor and Belle Haven — Oronoco Bay failed the most.  

Since 2010, Alexandria has been legally required to address excess bacteria in several Potomac tributaries -- Hunting Creek, Cameron Run, Holmes Run and Four Mile Run.  Bacteria’s sources include pet waste, overflows from the sewer system and wildlife droppings. The city’s multi-faceted action plan includes providing pet waste stations and requiring owners pick up after pets.  

Salt levels in waterways are rising across the United States, including Virginia’s and Maryland’s, largely from winter road and parking lot deicers.  “If these trends are not reversed, we may routinely surpass the taste threshold and EPA [Environmental Protection Agency] Health Advisory Levels. This could impact the local ecology and, from a drinking water perspective, the need for a costly change to our drinking water treatment processes,” according to Susan Miller, Fairfax Water’s Public Affairs Manager. Virginia American Water buys water for Alexandrians from Fairfax Water.

Salt is difficult for treatment plants to remove and elevated levels can pose risks to human health. Salt can also impair land and water, terrestrial and aquatic vegetation and harm birds and fish if they ingest too much.  

Plastic waste is exploding, says Martin Gary, executive director of the Potomac River Fisheries Commission. Not only does plastic disfigure shorelines, when it breaks down into tiny pieces, fish, birds, turtles and other critters can eat them and often do not excrete them. Ingested microplastics can injure organs, permeate cell membranes and leach hazardous chemicals.

They can also move up the food chain, starting with tiny zooplankton eating phytoplankton. The Four Mile Run Conservatory Foundation in 2020 documented microplastics in Four Mile Run water samples.  “Treated wastewater effluent was found to be a significant source of microplastic pollution, though microplastics were also found upstream of any influence from wastewater or tide-borne materials,” the Foundation reported.

Karl Berger worries about chemicals, like PCBs (polychlorinated biphenyls), PFAS (per- and polyfluoroalkyl substances) and endocrine disrupters linked to intersex fish, chemicals that persist for years.  Though banned in 1979, PCBs are still in the air, water and soil. PFAS chemicals are a group of emerging biotoxins used in many consumer products that pose a health risk to people and wildlife. Berger is Principal Environmental Planner for the Metropolitan Washington Council of Governments.

Alexandrian Nancy Rybicki, an aquatic plant ecologist, studies submerged aquatic vegetation (SAV) in the Potomac, underwater plants that provide food and habitat for many species and enhance water quality. Assessments in 2018 and 2019 found “significant losses of SAV populations,” likely because of record high rainfall which led to sediments that diminished water clarity.  2020 was wetter than 2018 in the region. Rybicki expects SAV to recover, but adds, “It sometimes takes years of good conditions for the SAV to recover.”  

As for fishing, a 2020 National Park Service study analyzed subsistence anglers along the river at five locations, including Jones Point and Little Hunting Creek.  Top species landed were blue catfish, striped bass, yellow perch and channel catfish.  The Virginia Department of Health has issued fish consumption advisories or warnings for many segments of the river for certain fish. For example, one advisory recommends against eating channel catfish because of PCBs in the Alexandria area. Another advises against eating large-mouthed bass and white perch more than twice a month.

The Elephant in the Room: Climate Change

“Climate change probably has the most meaningful impact on the future of the Potomac,” offers Kurt Moser, President, Four Mile Run Conservatory Foundation.  It is altering precipitation amounts and frequency and contributing to temperature variability.  Climate experts say that storms are becoming more intense and more frequent, which impacts fish, SAV, erosion and water quality overall.  Extreme precipitation events have increased by 136 percent from 2006-2017 compared to 1976-2015 in some places, reports the Northern Virginia Regional Commission.

A warming climate is making it “hotter and wetter in the basin,” comments Michael Nardolilli, executive director, Interstate Commission on the Potomac River Basin. “We will have wetter wets and drier dries,” more flooding and more variability, he predicts. States Berger: “Climate change makes everything worse in terms of water quality.  More flow means more sediment and nutrients, both nitrogen and phosphorus in the river.”  

Since the Potomac is tidal from its mouth up to Little Falls, sea level rise looms. The rate of relative sea level rise along the tidal Potomac is around 3.33 millimeters a year, equivalent to 1.09 feet over 100 years and rising, according to Geoffrey Sanders with the National Park Service. Sea level rise threatens to flood shorelines and move wetlands inland if they not blocked.  “The change in climate is underway and it is too late to expect the consequences can be avoided,” says Moser.  

Since the 1980s, the Chesapeake Bay has been warming at an average rate of 1.2 degrees every decade. Warming waters can harm aquatic fauna, and for some fish species, make the water inhospitable. “For any given area and for any given species, there will be winners and losers,” Patrick Geer with the Virginia Marine Resources Commission told the Virginia Mercury.

Hopeful Signs

With so many factors at issue, most experts are cautious in predicting the river’s future.

Maryland manages multiple water quality monitoring stations with the station closest to Alexandria at Fort Washington. The data show that, for example, from 2009 to 2019, the status of dissolved oxygen and phosphorus, is “good” and the trend is “improving.”  For nitrogen, the status is poor, but it too is improving.

Looking forward, many river watchers point to Alexandria’s $613 million River Renew project.  The city’s combined sewer overflow system, largely in Old Town dating to the 1800s, dumps 140 million gallons of untreated sewage mixed with stormwater during some heavy storms.  The largest infrastructure project in the city’s history, AlexRenew is building a tunnel system to capture and treat the sewage-rainwater mix before returning the cleaned water to the river.  Washington, D.C., has a similar project underway, the Clean Rivers Project, expected to cut combined sewage overflow by 96 percent.

Nardolilli sees the river’s future as bright, though he reminds, “We still can’t swim in portions of it at some times.” He cites the closures of Alexandria’s Gen On/Mirant Power Plant and the Luke Paper Mill upstream in western Maryland as positive signs. 

“The future of the Potomac River depends on what we do in the 14,670- square-mile basin that drains into ‘the nation’s river,’” he advises. “For 80 years, the Interstate Commission on the Potomac River Basin has been working with many area stakeholders toward a sustainable future for the Potomac, using science and outreach to enhance the river’s many uses for the generations that follow us.”

Potomac Riverkeeper watchdog Dean Naujoks opines, “We’ve made a lot of progress fixing Alexandria’s and D.C.’s sewage systems.  Ten years from now this river will be cleaner than it is today. That’s the legacy we want to leave for our children so they can swim in the river.  There will always be threats to the Potomac River, but the future health of the river continues to improve.” 

Nevertheless, he worries: “Every time it rains, pollution in the form of pet waste, lawn fertilizers, oil, brake dust, salt, single use plastics and trash flushes into storm drains and eventually the river. We have a lot of work to do to address urban stormwater pollution and to reduce agricultural runoff linked to concentrated animal feeding operations." 

Berger calls the river’s future “a mixed bag.”  “We can continue to make progress or our current progress could be swept away by the negative impacts of climate change.  Water quality may depend less on direct actions we take to reduce water quality impacts and more on the actions we take to address climate change.”

Conservancy President Hedrick Belin cautioned, “We’ve reached a critical turning point for the river and we can’t backslide now. We must pass stronger water protection laws and invest in natural defenses that will make our communities better prepared for our changing climate.  We must strengthen — not weaken — water protections so fishermen can eat their catch, children can safely swim and we can drink water without worry.” 

Come spring, the creek chubs will return with mouths full of pebbles to make their nests on the river’s bed.  The health of the river they return to largely depends on us.

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